302 A MANUAL FOR NORTHERN WOODSMEN 



The Forest Service has employed the Biltmore stick in 

 measuring large timber on the Pacific Coast and else- 

 where, and the tests applied have shown reasonable 

 accuracy. A careful analysis of sources of error 1 has devel- 

 oped the following: 



(a) Tilting the stick and holding it other than vertical 

 to the line of sight to the trees' center are practices to be 

 guarded against, but if reasonable care is used in manipula- 

 tion, errors are negligible. 



(6) In applying values derived from plots or tables to 

 the stick itself, regard must be had to its thickness. The 

 stick may well be beveled, or a steel spline may be inserted 

 into it to carry the graduations. 



(c) Errors arising from measuring a tree the narrow or 

 the wide way are greater than with the c'aliper; hence 

 cross measures are the more desirable. 



(d) It is very easy in practice to vary the distance 

 between the stick and the eye, and this introduces error 

 that is material, though in continued work successive 

 errors tend to balance. 



(e) Men of ordinary height have a constant tendency 

 to measure tree diameter not breast high, but higher, near 

 the eye level. 



To conclude, the Biltmore stick requires to be practi- 

 cally tested before use and constant care in application. 

 More liable to error than the caliper, in ordinary timber 

 it works less rapidly as well. While serviceable in its 

 field, its general use is not to be recommended. 



1 Bruce at previous reference. 



